/FI[ ]pathname
This option causes the preprocessor to process the specified header file. This option has the same effect as specifying the file with double quotes in an #include directive on the first line of every source file specified on the command line, in the CL environment variable, or in an command file. If you use multiple /FI options, files are included in the order they are processed by CL.
Output-File (/F) Options | Compiler Options | Setting Compiler Options | Specifying the Pathname